On April 14, 2011, the High Voltage Institute of Hubei Electric Power Research Institute adopted the ultra-high voltage frequency conversion resonance test equipment produced by Suzhou Huadian (complete equipment including: 300kW frequency conversion power supply, 300kVA excitation transformer, 250kV/6A×4 high-voltage resonance reactors, 1000kV AC substation Voltage withstand) successfully conducted 1000kV GIS AC withstand voltage test at Jingmen Station.